Abstract:Many “high resolution” releases on Blu-ray, DVD, and also some HD downloads are created by upsampling Redbook or 48-kHz data, a practice that draws frequent and quite vehement outcries of fraud. Yet at the same time upsamplers, both hardware and software, are commonly marketed to consumers and professionals now with the promise of boosting redbook sonics to near-equality with high resolution. What's going on? A panel of experienced mastering engineers, DAC, and DSP designers looks at the long-standing controversies and claims behind upsampling, as well as its uses in audio. The issues relating to down/up conversion go well beyond headroom and relate directly to hardware and software implementation, the design of low pass filters, consequences of signal processing, and mastering considerations related to the production and release of modern high quality discs and music files.